This application is a division of U.S. patent application Ser. No. 10/964763, filed Oct. 15, 2004 now abandoned.
The present invention refers in general to frames which can be used for supporting and stretching a flexible sheet material, for the purpose of manufacturing a panel system which can be used to carry out a variety of functions, each of which depends on the type of sheet material used and on the surface to which the sheet material is associated.
In the following description, the term frame is used both to indicate a closed structure consisting of a plurality of elongated elements connected to each other at their ends with the aim of keeping a sheet material stretched, and an open structure including at least an elongated element intended to be associated with an end of the sheet material to be stretched, the opposite end of the sheet material being connected with another elongated element or with a fastening device of a type known per se.
A frame adapted to support and stretch an artistic canvas or similar, is described in the Italian utility model application TO96U000103. It comprises a prismatic-shaped base frame having a peripheral tab which is intended to be surrounded by a sheet material to be stretched. A counter-frame having a shape corresponding to that of the base frame is mounted telescopically so as to be slidable outside of the base frame, and has a peripheral edge for anchoring the edges of the sheet material by means of removable fastening means. Corresponding through openings are formed both in the base frame and in the counter-frame to allow to insert elastic wedges, acting from the inside of the base frame, for changing the position of the counter-frame with respect to the base frame, in order to adjust the tension of the sheet material.
The frame of this document is not much fit to be used with sheet materials of large size, in which case also the base frame and the counter-frame should be very large. However, it is very difficult to assure that an effective mutual sliding may take place between a base frame and a counter-frame having very extended sides and relatively small sections. Moreover, this frame cannot be used to stretch a sheet material if the frame is fixed to a support surface, such as a wall surface, since it would require to operate from the inside of the base frame for changing the tension of the sheet material.
More specifically, the present invention relates to an elongated element.
An elongated element for a frame having the features defined above, is known from the Italian utility model application TO2000U000018. This application describes in particular a frame intended to support a stretched sheet material, such as a fabric, an artistic canvas, paper or similar. The frame consists of a plurality of elongated elements each of which includes a main profile and an auxiliary profile. Each main profile of the frame is rigidly connected to a pair of other main profiles which are arranged perpendicular at its ends. An auxiliary profile is hinged at the back of each main element, which is provided with a free longitudinal end having a tab for allowing an edge of the sheet material to be anchored by removable fastening means. A screw, which can be driven by a tool in order to change its extension between the auxiliary element and the main element, is arranged on each auxiliary element for adjusting the tension of the sheet material, so as to change the angle of the auxiliary profile with respect to the main profile and therefore the distance between the auxiliary profile and the main profile.
The main elements of the frame of this solution have however a structure which is not much fit to be fixed on a support surface, owing to the presence of the auxiliary profiles which are hinged at the back. At any rate, this structure would not allow to obtain in a simple and practical manner the adjustment of the tension of a sheet material supported by the frame when the latter is already fixed on a support surface.